Effect of photoperiod on ovarian maturation in Cheirodon interruptus (Teleostei: Characidae) / Efeito do fotoperíodo na maturação dos ovários em Cheirodon interruptus (Teleostei: Characidae)

Abstract Cheirodon interruptus is a ubiquitous small characid that inhabits the Pampean region and commonly used as bait. Its vast market is supplied from the wild population causing a significant environmental impact. In this study, we assess the effect of photoperiod on ovarian maturation in order to evaluate its potential as a tool to manipulate reproduction under artificial conditions. Four treatments in triplicate (light: dark, L: D) were tested: 24L: 0D, 12L: 12D, 0L: 24D and a progressive photoperiod corresponding to the daily photoperiod increments in wild during winter-spring transition, accelerated three times. The experiment was conducted for 45 days. Gonadosomatic index (GSI), oocyte mean diameter, vitellogenic oocyte proportions, plasma estradiol concentrations (E2), condition factor (Kn) and standard length were estimated. Values of mean GSI, oocyte diameter, vitellogenic oocyte proportions and E2 concentration were maximum in the progressive treatment indicating vitellogenesis stimulation. In turn the same parameters were minimum in the 24L: 0D, revealing the vitellogenesis inhibition. This study showed that photoperiodic regime play an important role in the onset of ovarian maturation in C. interruptus.

Resumo Cheirodon interruptus é um pequeno caracídeo amplamente distribuído na região Pampeana e comumente usado como isca. Seu vasto mercado se abastece de populações silvestres causando um impacto ambiental significativo. Neste estudo, investigamos o efeito do fotoperíodo no amadurecimento do ovário para avaliar o potencial deste fator como ferramenta para manipular a reprodução em condições artificiais. Quatro tratamentos foram testados por triplicado (luz: escuro, L: D): 24L: 0D, 12L: 12D, 0L: 24D e um fotoperíodo progressivo que simula as mudanças das horas luz na natureza e na transição de inverno a primavera, acelerado três vezes. O experimento se realizou durante 45 dias. O índice gonadossomático (GSI), o diâmetro médio dos ovócitos, a proporção de ovócitos vitelogênicos, as concentrações plasmáticas de estradiol (E2), o fator de condição (Kn) e o comprimento padrão foram estimados. Os valores médios de GSI, o diâmetro dos ovócitos, as proporções de ovócitos vitelogênicos e a concentração de E2 foram maximizados no fotoperíodo progressivo, indicando estimulação de vitelogênesis. Por outro lado, esses mesmos parâmetros resultaram mínimos no tratamento 24L: 0D, revelando um efeito inibidor da vitelogênesis. Este estudo mostrou que as variações de fotoperíodo exercem um papel importante no início vitelogênesis reprodutiva em C. interruptus .

Effect of photoperiod on ovarian maturation in Cheirodon interruptus (Teleostei: Characidae)

Abstract Cheirodon interruptus is a ubiquitous small characid that inhabits the Pampean region and commonly used as bait. Its vast market is supplied from the wild population causing a significant environmental impact. In this study, we assess the effect of photoperiod on ovarian maturation in order to evaluate its potential as a tool to manipulate reproduction under artificial conditions. Four treatments in triplicate (light: dark, L: D) were tested: 24L: 0D, 12L: 12D, 0L: 24D and a progressive photoperiod corresponding to the daily photoperiod increments in wild during winter-spring transition, accelerated three times. The experiment was conducted for 45 days. Gonadosomatic index (GSI), oocyte mean diameter, vitellogenic oocyte proportions, plasma estradiol concentrations (E2), condition factor (Kn) and standard length were estimated. Values of mean GSI, oocyte diameter, vitellogenic oocyte proportions and E2 concentration were maximum in the progressive treatment indicating vitellogenesis stimulation. In turn the same parameters were minimum in the 24L: 0D, revealing the vitellogenesis inhibition. This study showed that photoperiodic regime play an important role in the onset of ovarian maturation in C. interruptus.

Resumo Cheirodon interruptus é um pequeno caracídeo amplamente distribuído na região Pampeana e comumente usado como isca. Seu vasto mercado se abastece de populações silvestres causando um impacto ambiental significativo. Neste estudo, investigamos o efeito do fotoperíodo no amadurecimento do ovário para avaliar o potencial deste fator como ferramenta para manipular a reprodução em condições artificiais. Quatro tratamentos foram testados por triplicado (luz: escuro, L: D): 24L: 0D, 12L: 12D, 0L: 24D e um fotoperíodo progressivo que simula as mudanças das horas luz na natureza e na transição de inverno a primavera, acelerado três vezes. O experimento se realizou durante 45 dias. O índice gonadossomático (GSI), o diâmetro médio dos ovócitos, a proporção de ovócitos vitelogênicos, as concentrações plasmáticas de estradiol (E2), o fator de condição (Kn) e o comprimento padrão foram estimados. Os valores médios de GSI, o diâmetro dos ovócitos, as proporções de ovócitos vitelogênicos e a concentração de E2 foram maximizados no fotoperíodo progressivo, indicando estimulação de vitelogênesis. Por outro lado, esses mesmos parâmetros resultaram mínimos no tratamento 24L: 0D, revelando um efeito inibidor da vitelogênesis. Este estudo mostrou que as variações de fotoperíodo exercem um papel importante no início vitelogênesis reprodutiva em C. interruptus .

Avaliação ultrassonográfica do aparelho reprodutor em serpentes vivíparas da família Boidae / Ultrasonographic evaluation of reproductive tract in viviparous snakes Boidae family

A reprodução faz parte do ciclo de vida dos animais permitindo a perpetuação e a conservação das espécies. Em serpentes, existe uma escassez de informações técnicas a respeito do ciclo reprodutivo. Este estudo teve o objetivo de avaliar o aparelho reprodutivo por meio da ultrassonografia em serpentes vivíparas cativas da família Boidae, permitindo diagnosticar as diferentes fases reprodutivas. Foram avaliadas ultrassonograficamente onze serpentes adultas de quatro espécies da família Boidae: Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus e Epicrates cenchria pertencentes ao acervo do Museu Biológico do Instituto Butantan, São Paulo Brasil. Para a avaliação ultrassonográfica, as serpentes foram contidas fisicamente com gancho herpetológico e depois manualmente por aproximadamente 15 minutos. A avaliação foi feita aplicando-se gel acústico sobre a pele e posicionando o transdutor na linha lateral-ventral direita e esquerda, em região medial do corpo em sentido crânio-caudal. O exame ultrassonográfico permitiu avaliar todo o ciclo reprodutivo nas serpentes. Nas avaliações ultrassonográficas das fêmeas pode-se definir as fases de desenvolvimento ovariano e ovidutal. Os folículos ovarianos durante a fase pré-vitelogênica foram visualizados como homogêneos e anecogênicos, em forma de "cacho de uva". Já na fase vitelogênica, os folículos estavam maiores e mais ecogênicos seguidos uns dos outros, como um "colar de pérolas". Quando não houve cópula, os folículos foram reabsorvidos dentro do ovário retornando a fase pré-vitelogênica. Na fase pós ovulatória foram visualizados três estágios bem definidos de desenvolvimento fetal dentro do oviduto: 1) logo após a ovulação (e fecundação), somente o vitelo foi visualizado; 2) o vitelo ocupava 60% e o feto 40% do ovo e 3) o feto estava formado e não havia vitelo. Nos machos, os testículos foram visualizados como uma imagem homogênea e hipoecogênica quando se encontravam em estágio...

The reproduction is part of the animal life cycle allowing the perpetuation and conservation of the species. In snakes, there is a shortage of technical information about the reproductive cycle. The objective of this study was to evaluate the reproductive tract by ultrasonography in captive viviparous snakes of the Boidae family, allowing diagnose of the different reproductive stages. Eleven adult snakes of four species of the Boidae family were sonographically evaluated, Eunectes murinus, Boa constrictor constrictor, Corallus hortulanus and Epicrates cenchria belonging to the Biological Museum's collection of the Instituto Butantan, Sao Paulo Brazil. For the sonographic evaluation, snakes were contained physically with herpetologic hook and then manually for about 15 minutes. The evaluation was done by applying acoustic gel on the skin and positioning the transducer on the right and left side-ventral line, in the medial region of the body in the skull tail sense. Ultrasonography allowed the evaluation of the whole reproductive cycle in snakes. In sonographic evaluations of females were defined the stages of ovarian and ovidutal development. The ovarian follicles during the pre-vitellogenic phase were visualized as homogeneous and anecogenic, in a "bunch of grapes" distribution. In the vitellogenic stage follicles were larger and more echogenic, following each other as a "string of pearls". When there was no copula, the follicles were reabsorbed in the ovary returning to pre-vitellogenic phase. In the post ovulatory phase were seen three well-defined stages of fetal development within the oviduct: 1) just after ovulation (and fertilization), only the vitellus was visualized; 2) occupied 60% of the vitellus fetus and 40% egg and 3) the fetus was formed and no vitellus. In males, the testicles were seen as a homogeneous and hypoechoic image during the reproductive stage...

Histological description of oogenesis in chiton virgulatus (Mollusca: Polyplacophora) / Descripción histológica de la ovogénesis de chiton virgulatus (Mollusca: Polyplacophora)

This paper describes the oogenesis of Chiton virgulatus, based on histological observations under transmission and scanning electron microscopy. Three oocyte types were identified: i) previtellogenic oocytes with a mean diameter of 50±20.5 µm, surrounded by elongated follicular cells of approximately 5 µm, ii) immature vitellogenic oocytes with a mean diameter of 113±15.3 µm and small cytoplasmic projections denoting the onset of the oocyte hull development; adjacent to each projection are pores approximately 0.7 µm in diameter, and iii) mature vitellogenic oocytes with a mean diameter of 146±24.8 µm; the oocyte cytoplasmic projections grow and its apical zone becomes trident-shaped; follicular cells adopt a bulbous shape due to the growth of the elongation and can reach up to 20 µm in length. The morphology and ultrastructure of the projections of the mature vitellogenic oocyte, as well as the size of pores at their base, are specific to C. virgulatus; therefore, these features could be used in taxonomic or fertilization studies.

En el presente trabajo se describe la ovogénesis de Chiton virgulatus, utilizando histología y las técnicas de microscopía electrónica de barrido y de transmisión. Se identificaron tres tipos de ovocitos: i) ovocitos previtelogénicos con un diámetro promedio de 50±20,5 µm, rodeados por células foliculares de forma alargada y un tamaño de aproximadamente 5 µm, ii) ovocitos vitelogénicos inmaduros con un diámetro promedio de 113±15,3 µm, este tipo de ovocitos presentan pequeñas proyecciones citoplasmáticas, que indican el inicio del desarrollo del casco del ovocito. Adyacentes a cada prolongación se presentan poros con un diámetro aproximado de 0,7 µm y iii) ovocitos vitelogénicos maduros con un diámetro promedio de 146±24,8 µm, las proyecciones citoplasmáticas del casco del ovocito crecen y en su parte apical adquieren la forma de un tridente, las células foliculares, dado el crecimiento de la prolongación toman el aspecto bulboso y llegan a medir hasta 20 µm de longitud. La morfología y la ultraestructura de las proyecciones del casco del ovocito vitelogénico maduro, así como el tamaño del poro en la base de las proyecciones son particulares para C. virgulatus, dichas características podrían ser utilizadas en trabajos de taxonomía y fertilización.

Oocyte development and ovarian maturation of the black triggerfish, Melichthys niger (Actinopterygii: Balistidae) in São Pedro e São Paulo Archipelago, Brazil

The oogenesis is a key stage in the reproductive development of an organism, which can be best understood from histological analysis of ovaries in different maturity stages. In order to provide information on the reproductive biology of the black triggerfish, M. niger, in particular on its oogenesis process, this study aimed at identifying and characterizing the oocyte development stages and its organization within the different stages of ovarian maturation based on specimens from São Pedro e São Paulo Archipelago. In this present report, a number of 294 ovaries were histologically analyzed. It was verified that they are composed of ovigerous lamellae containing oocytes at different development stages. Five different stages of oogenesis were identified: young cells, with an average size of 12.9 ìm; previtellogenic oocytes (perinucleolar), with an average size of 53.5 ìm; cortical-alveoli oocytes with an average size of 83.1 ìm; vitellogenic oocytes, with an average size of 160.4 ìm and mature oocytes, with an average size of 289.8 ìm. In addition to the germ cells, some somatic structures were also identified, such as: ovarian wall, follicular cells and blood vessels. Based on the type and number of oocytes observed, four stages of ovarian maturation were identified: early maturation, represented by only 2.2% of the sample; middle maturation, represented by 9.9%; mature, represented by 44.2% and resting, represented by 43.9%. The identification of five oocyte development stages in the ovarians from M. niger, suggested that the specie follows a pattern similar to that described for other marine fish.

A oogênese é um estágio chave no desenvolvimento reprodutivo de um organismo, o qual pode ser melhor compreendido a partir de análises histológicas dos ovários em diferentes estágios de maturidade. A fim de fornecer informações sobre a biologia reprodutiva do cangulo-preto, M. niger, em especial sobre o seu processo de oogênese, este estudo teve como objetivo identificar e caracterizar as fases do desenvolvimento ovocitário e sua organização dentro dos diferentes estágios de maturação ovariana, baseado em espécimes do Arquipélago de São Pedro e São Paulo. No presente estudo, um número de 294 ovários foram analisados histologicamente. Foi verificado que eles são constituídos por lamelas ovígeras contendo ovócitos em diferentes estágios de desenvolvimento. Foram identificados cinco diferentes estágios da oogênese: células jovens, com tamanho médio de 12,9 ìm; ovócitos pré-vitelogênicos (perinucleolares), com tamanho médio de 53,5 ìm; ovócitos alvéolo-corticais, com tamanho médio de 83,1 ìm; ovócitos vitelogênicos, com tamanho médio de 160,4 ìm e ovócitos maduros, com tamanho médio de 289,8 ìm. Além das células germinativas, algumas estruturas somáticas também foram identificadas, tais como: parede do ovário, células foliculares e vasos sanguíneos. Baseado no tipo e número de ovócitos observados, quatro estágios de maturação ovariana foram identificados: início de maturação, representado por apenas 2,2% da amostra; média maturação, representado por 9,9%; madura, representado por 44,2% e em repouso representado por 43,9%. A identificação de cinco estágios do desenvolvimento ovocitário nos ovários de M. niger, sugere que a espécie segue um padrão semelhante ao descrito para outros peixes marinhos.

Histología del ciclo reproductor de hembras del pejelagarto Atractosteus tropicus (Lepisosteiformes: Lepisosteidae) enTabasco, México / Histology of reproductive cycle of tropical gar Atractosteus tropicus females (Lepisosteiformes: Lepisosteidae) in Tabasco, Mexico.

En el sureste de México A. tropicus es una especie de gran importancia ecológica, económica, cultural y para acuicultura, sin embargo, sus poblaciones silvestres han disminuido a causa de diversas actividades antropogénicas, por lo que se caracterizó el ciclo reproductor de A. tropicus, a partir de los cambios en los elementos germinales y somáticos durante la ovogénesis y la estructura de toda la gónada, información valiosa para el mejor manejo y aprovechamiento de la especie. Mensualmente se capturaron con redes de arrastres, seis hembras sexualmente maduras (N=72), durante un ciclo anual (octubre 2003-septiembre 2004), en poblaciones silvestres de la laguna de Pomposu del municipio de Jalpa de Méndez; Tabasco, México. Las hembras fueron sacrificadas por decapitación y los ovarios se procesaron por métodos histológicos convencionales, se determinó el diámetro entre 10-20 ovocitos en los diferentes estadios de desarrollo al azar. Se determinó mensualmente el índice gonadosomático (IGS), volumen gonadal (gV) y el diámetro del folículo (fD). Además, se identificaron ocho estadios de desarrollo de la ovogénesis: I: cromatina nucléolo, II: perinucléolo temprano, III: perinucléolo avanzado, IV: alvéolos corticales, V: vitelogénesis temprana, VI: vitelogénesis media, VII: vitelogénesis avanzada, VIII: maduración final. El ciclo reproductor la constituye cuatro clases: I.-Proliferativa, II.-Maduración inicial, III.-Maduración tardía, IV.-Regresión-proliferación. El análisis de la información obtenida de los valores encontrados del IGS, gV, fD, estadios de la ovogénesis y clases reproductivas, indican que en diciembre se reinicia el crecimiento de los folículos (previtelogenesis), de mar-zo-julio se presenta la captación del vitelo (vitelogenesis) y en agosto-noviembre se presenta la máxima actividad reproductora, al contrastar este patrón con los factores ambientales (temperatura, precipitación) se sugiere que estos pueden funcionar como un gatillo ambiental, en el desarrollo de la ovogénesis y el desove.

In Southeast Mexico, A. tropicus is a species with great ecological, economic, cultural and aquaculture value, however wild populations have diminished due to diverse anthropological causes. The objective of this study was to characterize the reproductive cycle of A. tropicus, with a description of complete gonad structure and the changes in germinal and somatic elements during oogenesis, for better management and use of this species. Six sexually mature females (N=72) were captured monthly with drag nets during one year cycle (October 2003-October 2004) in wild populations of Pomposu lagoon, municipality of Jalpa de Mendez, Tabasco, Mexico. Females were sacrificed by decapitation and the ovaries were processed by standard histological methods; the diameter of 10-20 oocytes taken at random was determined in different stages of development. Gonadosmatic index (GSI), gonadal volume (gV) and follicule diameter (fD) were determined monthly. Among results we could determine eight oogenesis developmental stages: I: chromatin nucleolus stage, II: early perinucleolus stage, III: mid perinucleolus stage, IV: advanced perinucleolus stage, V: early vitellogenesis stage, VI: mid vitellogenesis stage, VII) advanced vitellogenesis stage and VIII: final maturation stage. The reproductive cycle could be divided in four phases: I: proliferative phase, II: initial maturation phase, III: late maturation phase, IV: regressing phase. Analysis of the data obtained from the IGS, gV and fD values, oogenesis stages and reproductive phases, indicate that in December previtellogenesis phase restarts, from March through July yolk deposition (vitellogenesis) occurs, and from August to November the maximum reproductive activity takes place. Contrasting this pattern with local environmental factors such as temperature and precipitation, we suggested that these may serve as an environmental activator in the development of oogenesis and spawning of this species. Rev. Biol. Trop. 60 (4): 1857-1871. Epub 2012 December 01.

Ovary Development and Maturation in Nezara viridula (L.) (Hemiptera: Pentatomidae)

Ovary development and maturation of Nezara viridula (L.) were evaluated by examining ovariole morphology and the alterations in the biochemical (protein synthesis related to reproduction) composition of the hemolymph. Quantitative and qualitative protein analyses were performed and ovary structural alterations for the pre-reproductive and reproductive stages were recorded. Total concentration of proteins in female hemolymph gradually increased until the end of the pre-mating stage, remaining unaltered thereafter. Proteins linked to reproduction (vitellogenins) appeared in the hemolymph 10 days after adult emergence and indicated the end of the pre-mating stage. After mating, total protein concentration in the hemolymph was lower compared to virgin females; vitellogenin levels were similar during most of the observation period. Oocyte development and maturation were gradual and age dependent. Ten-day-old females had chorionated oocytes ready for fertilization. Mating did not stimulate oocyte development in N. viridula, but the lack of mating activity appeared to have stimulated oocyte resorption in 17-day-old females.

Culex quinquefasciatus vitellogenesis: morphological and biochemical aspects

The vitellogenic process in Culex quinquefasciatus, which is triggered by a blood meal, involves the synthesis, distribution and storage of the nutrients necessary for embryo development. The fat body of an adult female Cx. quinquefasciatus revealed two cell types: large trophocytes and small, eosinophilic, "oenocyte-like" cells, which show no morphological changes throughout the gonotrophic cycle. Trophocytes, which only begin to synthesise vitellogenin (Vg) 12 h post-blood meal (PBM), undergo a series of morphological changes following engorgement. These changes include the expansion of the rough endoplasmic reticulum (RER) and Golgi complex, which are later destroyed by autophagosomes. At 84 h PBM, trophocytes return to their pre-engorgement morphology. The ovarian follicles of non-blood-fed Cx. quinquefasciatus contain a cluster of eight undifferentiated cells surrounded by follicular epithelium. After engorgement, the oocyte membrane facing the perioocytic space increases its absorptive surface by microvilli development; large amounts of Vg and lipids are stored between 24 and 48 h PBM. Along with yolk storage in the oocyte, follicular cells exhibit the development of RER cisternae and electron-dense granules begin to fill the perioocytic space, possibly giving rise to endochorion. Later in the gonotrophic cycle, electron-dense vesicles, which are possible exochorion precursors, fuse at the apical membrane of follicular cells. This fusion is followed by follicular cell degeneration.

Desenvolvimento ovariano de Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), no reservatório de Pedra, Rio de Contas, Bahia / Ovarian development of Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), from the Pedra reservoir, Contas river, Bahia

O presente estudo tem por objetivo caracterizar a organização dos ovócitos e os estádios maturacionais do ovário da pescada Plagioscion squamosissimus. As coletas foram realizadas bimestralmente no reservatório de Pedra, rio de Contas (BA), entre novembro de 2004 e setembro de 2006. As análises microscópicas foram realizadas através de cortes histológicos, corados com hematoxilina - eosina - floxina e mistura tricrômica de Gomori. Através da análise macro e microscópica, foram identificados cinco estádios maturacionais. A coloração das gônadas variou de acordo com o desenvolvimento gonadal. Para o desenvolvimento ovocitário, foram definidas seis fases: ovogônia e perinucleolar; vitelogênica e lipídica inicial; vitelogênica e lipídica intermediária; vitelogênica e lipídica avançada e pré-ovulação. Foram observadas estruturas semelhantes às de peixes marinhos, como fusão de gotículas de óleo nas fases finais de maturação e hidratação pré-ovulatória. Estas características podem ser explicadas pela origem marinha da família Sciaenidae, indicando a necessidade de estudos mais detalhados para compreender o aparecimento, desenvolvimento e função dessas estruturas ao longo do desenvolvimento ovocitário.

This study aimed to characterize oocyte organization and maturation stages of Plagioscion squamosissimus ovary. Samples were collected bimonthly in Pedra reservoir, Contas River (BA), between November 2004 and September 2006. Microscopic analyses were made on histological cuts stained with hematoxylin - eosin - phloxine and Gomori trichromic mixture. Five maturation stages were identified through macro and microscopic analysis. Gonad coloration varied according to maturation stages. Six phases of oocyte development were identified: oogonia and perinucleolar, vitellogenic and early lipidic, vitellogenic and intermediate lipidic, vitellogenic and advanced lipidic, and pre-ovulation. Cell structures were similar to those found among marine species, such as oil droplets fusion at later developmental stages and pre-ovulatory hydration. Such features may be explained by the marine origin of Sciaenidae, thus suggesting the need of more detailed studies for understanding the origin, development and function of these structures along oocyte developmental stages.

Histological ultrastructural aspects fat body virgin physogastric queens Melipona quadrifasciata anthidioides lepeletier, 1836 (HYMENOPTERA, APIDAE, MELIPONINI)

Variations in the morphology and biochemical content of insect fat body have been associated withmetabolic activity and the reproductive cycle (synthesis of vitellogenin). In social insects such as bees,the functional traits of fat body also differ between workers and queens. In this work, we used light andtransmission electron microscopy to examine the morphological features of fat body trophocytes of virginand physogastric mated queens of the stingless bee Melipona quadriafasciata anthidioides before and duringvitellogenesis. Virgin queens had few, small fat body cells in which lipid deposits predominate, and showedno evidence of biosynthetic activity or the uptake of exogenous substances. In contrast, the fat body cells ofphysogastric queens were almost completely devoid of lipids, exhibit a well-developed rough endoplasmicreticulum with an obvious intraluminal product, and contained Golgi stacks that release numerous vesicles.These ultrastructural findings were suggestive of proteosynthesis. However, there was no evidence for theaccumulation of synthesized material in the form of secretory granules. We conclude that the trophocytes ofvirgin and physogastric queens differ basically in their switch from a storage role in the former to a syntheticrole in the latter. In addition, the high level of vitellogenesis seen in egg-laying queens suggests that themain material synthesized is vitellogenin.

Comparative Study of the Vitellogenesis in Autogenous and Anautogenous Strains of Aedes togoi / 第二军医大学学报

This report deals with the comparative study on the vitellogenesis in autogenous and anautogenous strains of Aedes togoi. Histochemical and immunohistochemical methods were used. It was found that rule of vitellogenesis is characteristic in different strains within the same species. Synthesis of vitellogenin in autogenous strain begins as soon as post-emergence and the process goes on continuously, up to the oocytes to take in vitellin for maturation. Vitellogenin synthesis in anautogenous strain starts after blood meal, and there is an apparent testing stage before blood feeding. The capacity of vitellogenin synthesis is also different between two strains.